Japan's government has been noticeably restrained in its statements about a bitter dispute with China over islets in the East China Sea. Anti-Japanese protests in China have spread to dozens of cities.

Fishing boats are seen departing Shenjiawan port in Zhoushan, Zhejiang province, toward the East China Sea fishing grounds, Sept. 17. China and Japan are currently involved in a territorial dispute involving a group of uninhabited islets in the East China Sea, called the Senkaku by Japan and Diaoyu by China.

Tokyo is running short of options in dealing with its increasingly assertive giant neighbor over disputed islands in the East China Sea, as the United States attempts to remain neutral and calls for calm from both sides.

In China, anti-Japanese demonstrations have now spread to as many as 100 cities as tensions mount over Japan’s purchase of islands it calls the Senkaku and China calls the Diaoyu. The islets, which were owned by a Japanese family, lie between the two countries.

China reacted angrily to the brief landing Tuesday of two Japanese protesters on the main island of the group, even as a large flotilla of Chinese fishing vessels and a separate group of surveillance ships were heading for the disputed territories.

“The unlawful landing of the Japanese right-wingers on the Chinese territory of the Diaoyu islands was a gravely provocative action violating Chinese territorial sovereignty,” said Foreign Ministry spokesperson Hong Lei in an issued statement.

The Japanese government has been noticeably cautious in its own recent pronouncements on the dispute, no doubt wary of inflaming passions further in China, where Sept. 18 is remembered as the day of the Liutiaohu (Manchurian) Incident that was used as an excuse by Japan to invade and occupy Manchuria.

Japan’s colonization of a large swath of northeast China is still regarded as one of the most humiliating incidents in recent Chinese history by many of its people.

“The government is trying to stop any further effects on Japanese people in China,” Japanese Chief Cabinet Secretary Osamu Fujimura said at a press conference in Tokyo on Tuesday, following reports of Japanese businesses in China being attacked and many companies suspending their operations there out of fear for employee safety.

At another press conference later in the day, when Chinese patrol boats had entered the territorial waters around the islands, Mr. Fujimura simply confirmed the ships had been sighted and referred reporters to the Japan Coast Guard for further details.

Though it doesn’t want to be seen as buckling under pressure from Beijing, the Democratic Party of Prime Minister Yoshihiko Noda has little strength with which to face an angry China, unpopular as it is at home and facing a general election it is likely to lose.

“All the Japanese government can really do is to wait patiently for the situation to cool down,” says Tetsuro Kato, professor emeritus of politics at Tokyo’s Hitotsubashi University. “It tried to rely on the US, but the US is insisting on neutrality over the territorial dispute. So it has few means with which to answer China’s aggression.”

The Liberal Democratic Party (LDP) opposition is currently in the middle of a five-way leadership contest to decide who will challenge the government at the next election, and likely be the next prime minister.

“The five LDP candidates are all calling for a tougher approach toward China, and such nationalistic tendencies are likely to come to the fore at the election,” says Professor Kato.

Businesspeople in both countries, however, along with the friends and relatives of the tens of thousands of Japanese living and working in China, say they are hoping for a peaceful and rapid end to the tensions.

“We had a joint venture with a Chinese company due to start soon, but it’s been put on hold for now,” says a manager at a media-related firm in Tokyo who asked not to be identified because of the sensitivity of the current situation. “Our Chinese partners want to get on with the business, too, but they can’t with the atmosphere at the moment.”

But with ships from both China and Japan now patrolling the area, even an accidental collision between a Japanese and Chinese vessel has the potential to spark a more serious incident, though the more immediate damage is likely to be economic.

Bilateral trade amounted to more than $340 billion last year, and with the eurozone’s troubles showing few signs of ending soon, Japanese and Chinese businesses need each other’s markets more than ever.